I had ring worm
ring worm the outer circle is alot darker than the inner cycle its extremly itchy and its spreads ring worm is bacteria as well as a parasite I now gross!!
Eczema can be any size/shape be really itchy and because you scratch it it starts to bleed, scratching can irritate the skin and can change colour slightly
never had a boil but I heard they hurt like a b2tch
skin cancer would be black and weould be tender to the touch google the word melanoma to get pics for skin cancer
most skin problems you do need to see a dr for
i needed cream (antitopical) for ring worm and hypocortisone for eczema which never goes away!!
Could be hormones for all we know that is why you need to have it diagnosed from a dr